The invention is based on a device for monitoring undercarriage components of rail vehicles for faults, comprising at least one vibration pickup.
The monitoring systems for undercarriages are becoming increasingly important in rail vehicle transportation. On the one hand, for safety reasons, these monitoring systems are required normatively and in guidelines. Examples of this are the following systems which are required throughout Europe by the TSI (Technical Specification for Interoperability—Official Journal of the European Community) for high speed trains:                On-board systems for detecting derailing,        On-board systems for hot-box detection and/or for detecting damage to bearings, and        On-board systems for detecting instability and/or defective shock absorbers.        
On the other hand, the use of undercarriage monitoring systems leads to the diagnosis and early detection of damaged components, critical states and other faults in order to achieve early and status-oriented maintenance. Objectives here are shorter downtimes, better utilization of components and therefore reduction of costs.
For example, in the ICE, a system for detecting unstable running is used, and in relatively new automatic underground railway systems a system for detecting derailing is used. These systems have in common the fact that they are constructed to function and act independently. Each of these systems uses dedicated sensors.
For instability detection, one or more sensors are usually mounted on the bogie frame, which sensors measure the lateral acceleration (in the transverse direction with respect to the direction of travel x) in a specific frequency range and generate an alarm message when a limiting value is exceeded.
DE 101 45 433 C2 and EP 1 317 369 describe a method and a device for monitoring faults in components of a rail vehicle, which method and device are also based on the measurement of acceleration values and are mounted on lateral damper brackets attached to the wagon body. The detection direction of the acceleration pickup is parallel to the direction of travel there.
An example of a method and a device for detecting derailing is described in DE 199 53 677. Here, measurement signals of an acceleration sensor which is arranged on an axle bearing are evaluated directly. The measured acceleration values are integrated twice and compared with a limiting value. The simple acceleration sensor has a detection direction in the direction of the vertical axis (z direction) of the rail vehicle. However, according to the document, acceleration sensors which simultaneously have detection directions in the direction of travel (x direction), in the transverse direction with respect to the direction of travel (y direction) and in the direction of the vertical axis (z direction). Such an acceleration pickup is what is referred to as a multiple pickup, i.e., it is actually composed of at least two, here three acceleration pickups, each of which measures in one detection direction. Such multiple pickups and their associated evaluation directions are, however, relatively expensive.
A further possible way of detecting derailing is provided by a pneumatic monitoring device which operates in a purely pneumatic way. A basis for such a monitoring device is UIC541-08 “Derailing detectors for goods wagons”. The device is located on the wagon body of the goods wagon and controls the vertical accelerations here. In this context, a spring/mass oscillator, which opens a pneumatic valve at a specific limiting value, is used as the sensor element.
The problem with these systems, in particular within the scope of the functions of the detection of instability and detection of derailing, is the high degree of expenditure on sensor systems because a large number of individual sensors are used at different installation locations.